Method and apparatus for location of a catheter tip

ABSTRACT

The present invention relates to a method and apparatus used to place a catheter having a distal end and a proximal end where the proximal end cannot be trimmed within a patient. The method and apparatus utilize a device operative in locating the tip of a catheter, which includes a detector assembly having a detector and a locator. The detector of the detector assembly is locked into positioned remote from the distal end of the catheter prior to inserting the catheter in the patient. The distal end of the catheter is trimmed, as to define a trimmed distal end, the detector is then unlocked and placed proximate the trimmed end. In the preferred embodiment the detector is locked into place proximate the trimmed distal end and the catheter is placed within the patient.

This application is a Continuation of application Ser. No. 08/782,518,now U.S. Pat. No. 5,749,835 filed Jan. 9, 1997 which is a File WrapperContinuation of application Ser. No. 08/644,734, filed on May 10, 1996,now abandonded which is a File Wrapper Continuation of application Ser.No. 08/301,869, filed on Sep. 6, 1994, now abandonded whichapplication(s) are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for locating thetip of a catheter positioned in biological tissue.

BACKGROUND

The treatment of certain diseases often requires infusion of drugs ormedicants into the body. When infusing such medicants, a caregiver willoften make a venipuncture with a cannula to access a vein, and thread acatheter through the vein to a desired location. The catheter includes adistal end, a proximal end and one or more lumens therebetween. Thedistal end of the catheter may be placed at a variety of locationsincluding the superior vena cava. The proximal end of the catheter isthen coupled to a portal within the body or passes exterior of the body.

Generally, portals are sealed reservoirs accessible through a septum.The portal is connected to the proximal end of the catheter andsubcutaneously implanted within the patient. Catheters which passexternal of the body include: PICC (Peripherally Inserted CentralCatheter) catheters, which access the superior vena cave through thecephalic vein in the arm; and chest catheters (often referred to asHickman catheters) which pass through a tunnel bored into the chest theninto the cephalic vein.

The prior art provides for methods and devices to locate the distal endof the catheter within the body as the catheter is inserted into thevein. For example, commonly assigned U.S. Pat. No. 4,905,698 to Strohlet al describes a method and apparatus for catheter locationdetermination. The method and apparatus of Strohl utilizes a sourcewhich generates an alternating magnetic field, and a detector positionedproximate the distal end of the catheter. The detector generates avoltage in response to the proximity of the field generated by thesource. The phase of the voltage in the detector shifts as the sourcepasses over it. By referencing anatomical landmarks at the time thephase shift occurs, the caregiver can determine the exact location ofthe detector, and thus the location of the tip of the catheter.

The method and apparatus of Strohl are advantageous because the tip ofthe catheter can be located without use of fluoroscopy. Fluoroscopyinvolves using x-rays to locate the distal end of the catheter.

After the catheter is implanted, medicants are delivered therethrough tothe desired location. Medicants are introduced either directly into thecatheter, as in the case of a PICC catheter or chest catheter, orthrough bolus injection or continuous infusion into the portal. Eachtechnique for delivering medicants has associated advantages which acaregiver evaluates in determining how medicants will be delivered to apatient.

In the prior art, catheters are sold in predetermined lengths. Often,the length of the catheter purchased does not meet the exact needs ofthe patient. In the case of catheters used in conjunction with portals,the caregiver positions the distal end of the catheter within thepatient, for example at the superior vena cava, and trims the proximalend so that the catheter is the proper length This is especiallynecessary when the length of the catheter is greater than the distancebetween the superior vena cava and the location of the portal. Thedistal end will be located, and the proximal end will be trimmed priorto connection with the portal.

If the device of Strohl has been used to locate the distal end of thecatheter, in connection with placement of a portal, the caregiver willremove the device of Strohl prior to trimming the proximal end of thecatheter. The device of Strohl is removed by disconnecting a couplingpositioned on an associated junction box. The caregiver then trims theproximal end of the catheter, fits the portal to the proximal end of thecatheter and places the portal within the patient.

Chest type and PICC catheters are also sold in predetermined lengthswhich do not often meet the needs of the patient. To place a chest orPICC catheter the caregiver would lay the catheter over the patient todetermine the proper length and trim the distal end. The catheter wouldthen be placed using fluoroscopy.

In the prior art, use of devices of the type described in Strohl U.S.Pat. No. 4,905,698 are not used with either chest or PICC typecatheters. Use of these devices in the prior art are limited to use withportals. In particular, the device of Strohl is secured within the lumenof the catheter so that the detector of Strohl is positioned at thedistal end of the catheter. When the distal end of the catheter has beenlocated the proximal end is trimmed. Both PICC and chest cathetersinclude permanent fittings on their proximal ends which cannot betrimmed. The device and method taught by Strohl cannot be used withcatheters which include fittings at the proximal end, such as PICCcatheters or chest catheters, because the proximal end of the cathetercannot be trimmed. Therefore, a need has arisen to provide an apparatusand method which permits the safe and convenient use of the device ofStrohl or other related devices with PICC and chest catheters.

SUMMARY OF THE INVENTION

The present invention provides a method for determining the location ofa tip of a catheter located in biological tissue. The catheter includesa distal end, a proximal end, and a lumen positioned therebetween. Themethod includes providing a source which develops an externalalternating magnetic field, to locate a detector, which is operable ingenerating a voltage when the source is proximate the detector. Thedetector is locked remote from the distal end of the lumen of thecatheter.

The method further includes the steps of trimming the distal end of thecatheter. The detector is then unlocked from within the lumen of thecatheter and positioned proximate the trimmed distal end of thecatheter. The catheter is then positioned within the biological tissueand the source is placed proximate the detector to locate the trimmeddistal end of the catheter.

The present invention also provides a catheter for use with a cathetertip location device. The catheter includes a proximal end, a distal end,and a lumen positioned therebetween, while the catheter tip locationdevice includes a source providing an alternating magnetic current and adetector positioned within the lumen of the catheter. The catheter tiplocation device is operable in detecting the position of the detectorpositioned within the lumen of the catheter. A lock is positioned at theproximal end of the catheter, the lock being selectively movable among avariety of locked positions, the lock operable in selectively lockingthe detector remote from the distal end in any position chosen by thecaregiver or manufacturer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a dual lumen chest catheter.

FIG. 2 is a cross-sectional view of the chest catheter taken along theline 2--2.

FIG. 3 is a front view of the catheter shown in FIG. 1 showing itsdistal end being trimmed.

FIG. 4 is a front view of a patient with the chest catheter of FIG. 3 inplace prior to removal of a detector.

FIG. 5 is a front view of a patient with the chest catheter of FIG. 3 inplace, with a device operative in locating the tip of the catheter inuse.

FIG. 5A is a front view of a patient with the chest catheter of FIG. 1,with the catheter in operation.

FIG. 6 is a front view of a PICC catheter having its distal end trimmed.

FIG. 6A is a front view of a patient with the PICC catheter of FIG. 6 inplace, prior to removal of the detector.

FIG. 7 is a cross sectional view of a detector assembly operative inlocating the tip of a catheter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed toward a method and apparatus forplacing a chest catheter or PTCC catheter within a patient. The catheterincludes a distal end, a proximal end, and at least one lumen positionedtherebetween. The proximal end of the catheter includes a lock fitting.The method involves the steps of providing a catheter having a lumen anda detector locked within the lumen of the catheter where the detector ispositioned remote from the distal end of the catheter. The detector isoperable in generating a voltage when a source is proximate thedetector.

The catheter is placed external to the body as to determine the properlength of the catheter. The distal end of the catheter is trimmed to theproper length, and then the detector is unlocked from within the lumenof the catheter. The detector is then repositioned proximate to thetrimmed distal end of the catheter and locked in place using the lockfitting. After the detector is repositioned, the catheter is positionedwithin the biological tissue and the source is placed proximate thedetector to locate the trimmed distal end of the catheter.

Referring now to the Figures in which like elements are numbered alike,the present invention is shown. The catheter shown in FIG. 1 is a duallumen chest catheter, while the catheter shown in FIG. 6 is a PICCcatheter. A significant difference in structure between the chestcatheter of FIG. 1 and the PICC catheter of FIG. 6 is dimension and thenumber of lumens each may contain. For example, the greater diameter ofthe chest catheter shown in FIG. 1 permits the multiple lumens disclosedin FIG. 2. However, the method and apparatus of the present invention isnot precluded from use in multi-lumen PICCs.

With initial reference to FIG. 1, there is shown a catheter 100 having afirst proximal end 102, a second proximal end 104 and a distal end 106.Catheter 100 of the first preferred embodiment includes three portions,which are connected by a Y shaped member 108. Generally these portionsare a lower portion 110 and two pigtail portions 112, 114.

Lower portion 110 of catheter 100, as shown in FIG. 2, includes a firstlumen 116 and a second lumen 118 separated by a septum 119. First lumen116 connects distal end 106 to a first pigtail and first proximal end102 and second lumen 116 connects distal end 106 to second pigtail andsecond proximal end 104. In one preferred embodiment, first lumen 116has a larger lumen than that of second lumen 118.

Positioned on lower portion 110 between Y member 108 and distal end 106is a cuff 120. Preferably, cuff 120 is constructed from Dacron, aregistered trademark of E. I. Dupont De Nemours. (Dacron is a polyesterfiber typically made from Polyethylene terephthalate.) Cuff 120functions to anchor catheter 100 within the biological tissue afterplacement. Specifically, and with reference to FIG. 4, there is shown achest catheter, which when implanted within a patient passes through atunnel 250 bored within the chest of the patient. Catheter 100 isanchored by the biological tissue surrounding cuff 120 in tunnel 250which grows into cuff 120. Cuff 120 then assists in preventing infectionwithin the patient.

Referring to FIGS. 1 and 3, a pair of fittings 132 and 134 are attachedto first and second proximal ends 102, 104 of catheter 100,respectively. Fittings 132 and 134 facilitate connection of catheter 100to other medical devices, such as an infusion pump (not shown), whichoperates to deliver medicants through catheter 100 to the superior venacava, for example.

In the first preferred embodiment of the present invention, a lockingfitting 140 is attached to first proximal end 102 of catheter 100 atfitting 132. Locking fitting 140 is preferably a locking hemostasis typevalve which includes an aperture which decreases in size in response totwisting the valve. Hemostasis type valves ordinarily are used toprevent blood flow out of the patient through the catheter.Specifically, locking fitting 140 operates to lock a detector assembly200, of an apparatus for locating the tip of the catheter, into place.The apparatus for locating the tip of the catheter is of the typedescribed in commonly assigned U.S. Pat. No. 4,905,698 the disclosure ofwhich is fully incorporated herein by reference.

Referring to FIGS. 5 and 7, detector assembly 200 generally includes adetector 220 which has a magnetic core 210 wrapped by a wire 212. Wire212 includes a first end and a second end both of which are connected toan electronic controller 230. Magnetic core 210 including wire 212 whichis wrapped therearound is generally referred to as detector 220. Thedetector assembly 200, as described in U.S. Pat. No. 4,905,698, islocated in hollow jacket 225, while the detector is located at the tipof the hollow jacket.

In the preferred embodiment of the present invention detector assembly200 is locked within first lumen 116 of lower portion 110 of catheter100 proximate cuff 120. Detector assembly 200 is locked into position bylocking fitting 140. In the first preferred embodiment, detectorassembly 200 passes through locking fitting 140, which operates tocapture hollow jacket 225 of detector assembly 200.

As shown in FIG. 3 fittings 130 and 132 are positioned on the proximalends 102 and 104 of catheter 100. Because fittings 130 and 132 arepositioned on proximal ends 102 and 104 of catheter 100, a caregivercannot first place catheter 100 and then trim the excess catheter lengthoff of the proximal end as taught by the prior art. In the presentinvention, the caregiver first lays catheter 100 on the patient todetermine the approximate length of catheter 100 necessary for thespecific patient. The proper length is determined by the caregiverthrough reference to anatomical landmarks on the patient.

The caregiver then trims distal end 106 of catheter 100, as to define atrimmed distal end 107, as shown in FIG. 3 so that it is the properlength. Once catheter 100 is trimmed to the proper length, the caregivercan loosen locking fitting 140 and reposition detector 220 of detectorassembly 200 at trimmed distal end 107 of catheter 100.

The catheter can then be placed into the biological tissue using thetechniques of commonly assigned U.S. Pat. No. 4,905,698, which has beenpreviously incorporated by reference. The method and apparatus describedin U.S. Pat. No. 4,905,698 involves the use of detector 220, a source,shown as 235 in FIG. 5, and a locator 240. Source 235 generates analternating magnetic field which is placed proximate detector 220 by alocator 240. Detector 220 generates a voltage in response to themagnetic field when locator 240 is proximate detector 220. As statedabove, detector is positioned proximate trimmed distal end 107 ofcatheter 100. The phase of the voltage generated by detector 220 shiftsas locator 240 passes over it. By referencing anatomical landmarks atthe time the phase shift occurs, the caregiver can determine thelocation of detector 220, and thus the location of trimmed distal end107 of catheter 100.

Once the trimmed distal end 107 of catheter 100 is placed, and located,locking fitting 140 is loosened and detector assembly 110 is removed.Detector assembly is removed by pulling it through lumen 116 of catheter100.

As shown in FIG. 5A, fittings 130 and 132 may each then be connected toa mating fitting 133 from a pump (not shown) or another catheter (notshown). In this fashion medicants may be delivered through the catheterto the patient.

It is to be understood that the above described method and constructionis intended for use with any catheter, regardless of how many pigtailends, which has a fitting or other structure on its proximal end andtherefore prohibits the trimming of its proximal end after placement.Further, it is to be understood that the above-described method includesalternate methods of catheter tip location which include insertion orremoval of a detector.

With reference to FIGS. 6 and 6A, an example of a second type ofcatheter which includes a fitting at its proximal end is shown.Specifically, the catheter shown in FIG. 6 is a PICC catheter 300. PICCcatheter 300 accesses the cephalic vein proximate the arm of the patientand travels therethrough to the superior vena cava, where medicants maybe delivered. As above, PICC catheter 300 includes a detector assembly200 placed within its lumen, not separately shown, with detector 220 ofdetector assembly 200 positioned distal from the distal end of PICCcatheter 300.

Generally, and with reference to FIG. 6, PICC catheter 300 does notinclude pigtails as the diameter of the lumen of PIC. catheter 300 istoo small. PICC catheter 300 includes a distal end 304 having a fitting330 and a proximal end 306. To place PICC catheter 300 using the methodof the present invention, a caregiver places PICC catheter 300 over thepatient to estimate the approximate length of PICC catheter 300, in afashion similar to that described above. As shown in FIG. 6, thecaregiver then trims distal end 304 as to define a trimmed distal end305 of PICC catheter 300.

Once the distal end of PICC catheter 300 has been trimmed, a lockingfitting 341, preferably a locking hemostasis type valve, may be loosedand detector 220 of detector assembly 200 may be placed proximatetrimmed distal end 305 of PICC catheter 300. PICC catheter 300 may thenbe placed using the method taught in U.S. Pat. No. 4,905,698 to Strohl,previously incorporated by reference.

The present invention includes significant advantages over the priorart. These advantages include minimization of steps necessary inpositioning a catheter. Minimization of the seeps reduces theopcortunity for error to occur. Errors which may occur in the placementof the catheter include cutting the detector assembly and unnecessaryplacement of catheters which have an improper length.

Additionally, PICC type catheters which travel a relatively greatdistance within the body can now be tracked using the non-intrusivemethod taught by U.S. Pat. No. 4,905,698 to Strohl. This is asignificant advantage in view of the various body pathway"intersections" which a PICC type catheter must pass, on its way to thesuperior vena cava, in which the catheter can deviate from its intendedpath during placement. If such deviation goes unchecked it can result indelivering much needed medicants to the wrong location.

While the foregoing detailed description of the present inventiondescribes the invention of the preferred embodiments, it will beappreciated that it is the intent of the invention to include allmodifications and equivalent designs. Accordingly, the scope of thepresent invention is intended to be limited only by the claims which areappended hereto.

What is claimed is:
 1. A catheter location system allowing location ofan end of the catheter, said catheter location system comprising:acatheter including a proximal end, a distal end, and a lumen positionedtherebetween; a catheter detector positioned within the lumen of thecatheter; and a lock positioned at the proximal end of the catheter, thelock being selectively movable between a locked position and an unlockedposition for locking and unlocking the catheter detector within thelumen.
 2. The catheter location system of claim 1, further comprising asource providing an alternating magnetic current.
 3. The catheterlocation system of claim 1, wherein the proximal end of the catheterincludes a fitting.
 4. The catheter location system of claim 1, whereinthe lock comprises a locking hemostasis valve.
 5. The catheter locationsystem of claim 1, wherein the catheter is a chest-type catheter.
 6. Thecatheter location system of claim 1, wherein the catheter is aperipherally inserted central catheter.
 7. The catheter location systemof claim 1, wherein the catheter detector is locked within the lumen ofthe catheter remote from the distal end of the catheter.